Joe Root has insisted he is 100% committed to selecting Alastair Cook for the rest of the Test series against India.

Cook is the most prolific batsman in England's Test history but is averaging just 19.21 in the eight Tests he has played this year and 16.00 in this series against India. He has also earned an unwanted record as the most unreliable slip catcher in Test cricket since the start of 2015.

But Root, England's captain, believes Cook's modest form can be explained, in part, by the seam-friendly conditions in which recent games have been played. And he backs Cook's experience to find a way through his current struggles.

"Alastair Cook is a world-class performer," Root said. "He's proven that time and time again. I'd like you to write him off because every time he's written off he comes back and scores a double-hundred.

"We have to be realistic about the surfaces we've been playing on. Throughout the whole summer, they've been very much tailored around seam bowling and we've had some very bowler-friendly conditions. There's been a lot of cloud cover, the ball has seamed around quite a lot and it's obviously swung as well. And the hardest point to bat is opening. Both sides' top orders have struggled and it might be that's the case again in Southampton.

"But there's no one with more experienced currently in Test cricket than him. If you watch him apply himself in training, or the way he goes about his practice, he doesn't look like someone who is thinking about jacking it in. He seems very dedicated. I'm sure he will be calling upon all of that going into that game and giving himself the best chance. Yes, 100% I want him for the rest of the series."

While there has been a suggestion that Cook may miss the fourth Test in Southampton to be at the birth of his third child, Root was confident he should still be available for the match, starting on August 30.

"I don't think the due date is for a while yet but these things are not an exact science," Root said. "We'll play things slightly by ear but, as far as I'm aware he's going to be available for selection."

Alastair Cook punches down the ground AFP

Root also hinted that, should Jonny Bairstow be unable to keep in Southampton, the decision to give Jos Buttler the gloves would be "very easy". Bairstow sustained a fractured finger at Trent Bridge and, while England remain hopeful he will be fit to play as a batsman, it seems the chances of him keeping are slim. Once he was forced off the field at Trent Bridge, Buttler took the gloves without drama and then registered his maiden Test century.

"Jonny is obviously a world-class batter in good form and would warrant his place within the side as a batter," Root said. "In terms of keeping, we are very fortunate to have Jos in the team already and it would make things very easy in terms of him stepping into that role."

But while Root accepted England's first-innings batting had been "very poor" during the third Test, he took encouragement from the second-innings stand of 169 between Buttler and Ben Stokes.

"That partnership between Jos and Ben is a great example and lesson to the batting group of how to go about things in Test cricket," Root said. "We saw two guys who are generally very attack-minded adapt to a situation - still probably in bowler-friendly conditions - and find a way to build a very strong partnership and put India's bowlers under pressure.